The present invention relates to a carrier for an olefin polymerization catalyst. Particularly, it is concerned with a process for preparing a carrier suitable for the preparation of polyolefins comprising spherical particles having a good flow characteristic.
Heretofore, in this technical field there have been known many catalysts comprising an inorganic magnesium solid as carrier such as a magnesium halide, magnesium oxide or magnesium hydroxide and a transition metal compound such as a titanium compound or a vanadium compound supported on the carrier. However, the polymers obtained by using those known catalysts generally comprise particles having a low bulk density, a small average particle size, an amorphous shape and a wide particle size distribution including a large proportion of fine particles. Because of these disadvantages, there has been a keen desire for improvement from the standpoint of productivity and slurry handling. Furthermore, when molding those polymers, there arise problems such as the generation of dust and lowering of the molding efficiency, and consequently it has been strongly desired to increase the bulk density and average particle size and decrease the proportion of fine particles.